Conventionally, to apply a lithium-ion battery (LIB) to industrial equipment or in-car equipment, it is necessary to connect multiple cells in series to form a battery assembly because a voltage produced by a single cell is low.
In contrast, a number of mid-size and large-size electrically-powered equipment using a lead battery with the average operating voltage of about 48 volts (V) have been provided.
In recent years, there is a growing trend to replace a lead battery with a high-performance lithium-ion battery. In this case, for example, a mid-size or large-size electrically-powered equipment with the average operating voltage of 48 V is required to operate with the maximum charge voltage of 60 V and the discharge cut-off voltage (minimum discharge voltage) of about 30 V that is the lower limit of the performance of a motor of the equipment.
Incidentally, to meet a demand to supply a large amount of power, a system using the battery assembly as a drive power supply or an auxiliary power supply is increasingly required to have a large capacity to improve performance and increase uptime.
Therefore, in order to meet the aforementioned demand, there has been used a battery assembly device comprising battery groups connected in parallel with each other. Here, each of the battery groups is formed by connecting a number of batteries in series.
Meanwhile, to simplify battery handling, in some cases, a battery module may be formed by connecting multiple batteries in parallel or in series as a module.
Furthermore, in some cases, a battery management unit (BMU) may be used as a control device to control multiple battery modules of the battery assembly device.
In this case, the BMU and each of the battery modules are connected via a communication connector included in a communication line for control and via a positive connector (positive connection cable) and a negative connector (negative connection cable) included in a power supply line.
Incidentally, in some cases, the positive connector or the negative connector may be disconnected for maintenance to check a deterioration or failure of a battery of the battery module while the communication connector remains connected.
When the positive connector or the negative connector is disconnected while the communication connector remains connected, and if the positive connector and the negative connector are erroneously connected to reestablish the power supply line, a short circuit condition occurs.
Therefore, a fuse element may fuse and the reestablishment may become burdensome.